Roland Juno-106 (Part Five - Sliders And Buttons)

Summer vacation had arrived. I finally had time to do all the work on the Juno-106 that I needed to do. And there was still quite a bit that needed doing: new battery, new tact switches, rebuilding the sliders, cutting out fader dust covers, and doing something about those ugly buttons. Being a junior high school teacher, I had the whole summer off to get things done. Here’s how it went.

Starting with the battery seemed like a good idea. Although the old one was still putting out a good amount of charge, I figured since I was ripping everything out I may as well get the module board out too. I unplugged the numerous amount of cables, got the board out, and swapped out the battery. No sweat.

The next order of business was getting the panel board out from under the top of the synth to deal with all the things that needed addressing there. Out came the many cables running into the panel board, off popped the slider caps, and out slid the board from its slot under the panel. I pulled out the bender assembly as well, as that was going to need its sliders refurbished along with the main array up top.

I looked at the mess of cables I made and suddenly wished I had documented it all better. This would come back to bite me in the ass later.

With the front panel open, I could now see the small dent under the filter section more easily. It wasn’t big enough to notice unless you were looking for it but it was big enough that I wanted to fix it. I wonder what caused this dent? I can’t imagine anyone ever hitting a Juno-106. How could you ever get mad at this sweet thing? No, something probably fell on it in an earthquake. This being Japan, it happens. I actually have a dent in the railing around my loft from where a monitor bounced off it during a quake. It almost broke my leg when it finally hit the floor below. Good times. Back to the dent, I tried pushing on it from the underside but it wouldn’t budge. I didn’t want to risk making it worse, or cracking the paint, so I decided to leave it alone. Truthfully I hardly ever notice it.

Next, I desoldered all the faders from the panel board and bender board, and left them to soak in isopropyl alcohol overnight. I bought a glass jar with a screw-on lid for just this purpose. I suppose plastic wrap and a rubber band might have been good enough, but I didn’t want to wake up dead from asphyxiation. No garage or even separate room in my Tokyo rabbit hutch. Getting the hardened dust cover foam sheet off the faders was a little tricky, but I used a hobby knife to slice sideways and managed to not make too much of a mess. Whatever was left sticking to the sliders would get removed in the alcohol bath.

With the faders removed I could now concentrate on changing the tact switches. Nothing too unusual here. I just desoldered all the old ones, popped them out, and soldered in the new ones. What with all the faders and switches in this thing, I really wished I had a desoldering gun or something like that. I’m pretty good with the braid but it takes a long time, but sometimes the solder just doesn’t want to come up. I’m OK at the manual vacuum pump but I still need to work on my angle. I also occasionally burn the board or lift a solder pad and that’s really annoying. Maybe someday I’ll spring for a desoldering gun.

Back to the Juno, it was now time to take apart the faders for a good cleaning. As I learned from my RS-09, orientation of faders is important. I was very careful to keep everything oriented the same way, using the tabs on the bottom as landmarks. I used a tiny precision screwdriver to pry open the tabs, carefully removed the track, cleaned out the inside of the housing and the top of the track with a cotton swab, sprayed a little DeOxit Fader Lube on the track, and then coated the inside of the housing with DeOxit Fader Grease. I also made sure that there was nothing sticking to the tiny, delicate arms that reach down from the bottom of the moving “car” part that connects with the track. I put it all back together, again mindful of the orientation, and used the screwdriver to push the tabs back down, no small feat considering how lubed up and slippery everything was.

The most difficult part of this procedure was doing the bender faders. They’re extremely small and delicate, and, like the HPF switch, can not be replaced. You broke it you lost it, as it were. Of course, I did break one. Or at least I snapped off a pin on the bottom. Luckily, I was able to get it soldered back on but because of the bend in the pin I couldn’t get it back on perfectly. But it was good enough.

With all the faders reassembled and moving lickety split, I soldered them back in. During all the painstaking work that this procedure required, I kept kicking myself for not just leaving them alone. It’s not like they didn’t work. They were just a little stiff. But now that they’re done I’m so happy I did the work. They’re so smooth now and just a joy to use.

But I’m getting ahead of myself. There was a little more pain to experience before the joy. I plugged all the boards back in, turned it on, and nothing. Not even LEDs or numbers. It was at this point that I wished I had taken pictures of the cabling. After trying different combinations of cables and plugs, and looking at pictures online, I finally got it sorted. Later it occurred to me I could have used the service manual to do this as well. But all’s well that ends well.

But of course it wasn’t over yet. The HPF switch was completely dead and the bender board was doing really weird things. Cool, odd bendy things but not typical Juno things. First, the high-pass filter. I took it apart again and checked it with a multimeter. I was definitely getting readings at all the notch points. My issue was the little arm that connected with the track had gotten bent in reassembly and wasn’t making contact. I gently worked it back into place and put it back together. Success. Remember that the HPF switch has two tracks and two arms but only one is actually used.

Next, I removed the three bender board faders and took them all apart. The multimeter confirmed they were OK. A visual inspection revealed the same issue as the HPF switch: bent arms. I guess I bent them ham-fistedly putting them back together after cleaning. After fixing the arms (and resoldering my pin fix, which broke again) I got them back in. That did it and now they work fine.

It wasn’t time to celebrate yet as there was still more work to do. As you might remember from my Yamaha SK20 restoration, I had some acrylic felt leftover and planned to use that to make fader dust covers, but I read online that they can shed over time so I tried foam instead. Taking a direct tip from the guy currently restoring a Jupiter-8, I bought a sheet of 1mm black EVA foam off eBay. I did my best to cut out sheets of it. Laser-cut would be best but I don’t have a laser gun (haha, joke) so I used scissors. It looks like junk but it works.

The last order of business was getting the buttons looking new. For the algae-green ones I spray-painted them blue. They’re a little darker than I’d like but miles better than before, and I can always paint them again if I find a better color. For the white, I soaked them in peroxide and left them out in the sun for two afternoons to bleach them. Probably one afternoon would have been good enough, as the peroxide weakened a few of the buttons so they didn’t sit properly on their tact switches. I stuck a small, folded piece of foam sheet in between the button and switch and that brought them inline. Be careful with bleaching plastic. You can ruin it if you go too far.

With everything back together, I loaded in the factory presets from this site. I almost freaked when I got to bank B and found it empty but then realized that the banks have to be loaded separately.

Looking back, it was a lot of work to restore this Juno-106. Was it worth it? Yes, by all means. It’s such a joy to play now. In fact, I’ve been ignoring my other synths because I just can’t get enough of it. I even did this cover of “Comfortably Numb,” mainly with the 106.



I also have a huge sense of satisfaction at having finished this restoration. I accomplished a lot. I failed a few times, but I learned from my mistakes and never gave up. That’s success in my book.